TEM mode capacitance loading coaxial resonant cavity for P-band klystron

Abstract

The utility model belongs to the technical field of high-power microwaves, and particularly relates to a TEM mode capacitor loading coaxial resonant cavity for a P-band klystron, which comprises an outer conductor, two ends of the outer conductor are respectively and fixedly connected with a first blocking plate and a second blocking plate, a first cavity is arranged in the outer conductor, an inner conductor is arranged in the first cavity, and a second cavity is arranged in the inner conductor. The length of the inner conductor is smaller than that of the outer conductor, one end of the inner conductor is fixedly connected with the side, close to the second blocking plate, of the first blocking plate, a gap is formed between the other end of the inner conductor and the side, close to the first blocking plate, of the second blocking plate, the gap is L1, a gap is formed between the outer side wall of the inner conductor and the inner side wall of the outer conductor, and a second cavity is formed in the inner conductor. A first through hole is formed in the first blocking plate and communicated with the first cavity through the second cavity, and a second through hole is formed in the second blocking plate in the length direction of the outer conductor and communicated with the first cavity. Compared with a double-in cylindrical resonant cavity, the transverse size of the resonant cavity is obviously reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of high-power microwave, and particularly relates to a TEM-mode capacitively loaded coaxial resonator for a P-band klystron. Background Technique

[0002] P-band high-power klystrons can be used in major equipment such as long-range radars and large particle accelerators. The resonators of such klystrons generally adopt double-entry cylindrical resonators or double-entry rectangular resonators, and the working mode is the TM010 mode. Since the wavelength in the low-frequency band of the P-band is relatively long, according to the resonance size co-frequency effect, the size of the resonator is also relatively large. Taking a ready-made commercial P-band high-power klystron as an example, its length is about 5 meters, and the transverse radius is about 0.8 meters. The large volume leads to a large floor area, increasing the construction cost of the entire long-range radar and large particle accelerator device. For example, the proton linear accelerator of the first phase of the China Spallation Neutron Source (CSNS) uses 5 P-band 324 MHz megawatt-class klystrons as the power source of the linear particle acceleration cavity, and these power sources occupy nearly 200 square meters of laboratory area. And the superconducting linear accelerator of the second phase of the China Spallation Neutron Source (CSNSII) plans to use 26 P-band 648 MHz klystron power sources. If the double-entry cylindrical resonator or double-entry rectangular resonator scheme is still adopted, its floor area will be even larger. In addition, the weight caused by the large volume is not conducive to the later installation, operation, and maintenance of long-range radars and large particle accelerator devices.

[0003] Therefore, it is necessary to design a TEM-mode capacitively loaded coaxial resonator for a P-band klystron to solve the above problems. Content of the Utility Model

[0004] The purpose of the utility model is to provide a TEM-mode capacitively loaded coaxial resonator for a P-band klystron to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the utility model provides a TEM-mode capacitively loaded coaxial resonator for a P-band klystron, which comprises an outer conductor. Both ends of the outer conductor are fixedly connected with a first end plate and a second end plate respectively. A first cavity is arranged inside the outer conductor. An inner conductor is arranged inside the first cavity. The length of the inner conductor is less than that of the outer conductor. One end of the inner conductor is fixedly connected with the side of the first end plate close to the second end plate. A gap is arranged between the other end of the inner conductor and the side of the second end plate close to the first end plate, and the gap is L1, where L1 is a constant. A gap is arranged between the outer side wall of the inner conductor and the inner side wall of the outer conductor. A second cavity is arranged inside the inner conductor. A first through hole is formed in the first end plate, and the first through hole communicates with the first cavity through the second cavity. The second end plate is provided with a second through hole along the length direction of the outer conductor and communicates with the first cavity.

[0006] Preferably, the cross sections of the outer conductor, the first cavity, the inner conductor, the second cavity, the first end plate and the second end plate are all circular.

[0007] Preferably, the first end plate, the inner conductor and the second end plate are all coaxially arranged with the outer conductor.

[0008] Preferably, the outer conductor, the first cavity, the inner conductor, the second cavity, the first end plate and the second end plate are an integral body.

[0009] Preferably, the outer diameter of the inner conductor is Φ2, the inner diameter of the inner conductor is Φ1, and the relationship between the outer diameter and the inner diameter of the inner conductor is: Φ2 = 2Φ1; both Φ1 and Φ2 are constants.

[0010] Preferably, the diameters of the first through hole and the second through hole are both equal to the inner diameter of the inner conductor.

[0011] Preferably, the length of the outer conductor is L2; the relationship between L1, Φ1 and L2 is: Φ1 < L1 < 1 / 5 times of L2, and L1 is a constant.

[0012] Compared with the prior art, the utility model has the following advantages and technical effects:

[0013] The TEM-mode capacitively loaded coaxial resonator for a P-band klystron provided by the utility model enables the working mode to be a quasi-TEM mode, breaks the size common-mode effect in the TM 010 mode, and thus reduces the transverse size of the resonant cavity body. Compared with the double-entrance cylindrical resonant cavity in the TM 010 mode, the transverse size is significantly reduced. Description of the Drawings

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings:

[0015] Figure 1 FIG. is a schematic structural diagram of a TEM-mode capacitively loaded coaxial resonator for a P-band klystron proposed by the present invention;

[0016] Figure 2 is Figure 1 a sectional view taken along line A-A in;

[0017] Figure 3 FIG. is the TEM-mode electromagnetic field distribution of the capacitively loaded resonator in the present invention;

[0018] Figure 4 FIG. is the equivalent resonance circuit of the capacitively loaded coaxial resonator in the present invention;

[0019] Wherein: 1. Outer conductor; 2. Inner conductor; 3. First end plate; 4. Second end plate; 5. First through hole; 6. Second through hole; 7. Second cavity; 8. First cavity; 9. Equivalent transmission line; 10. T reference plane; 11. Equivalent capacitance. Detailed implementation manners

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific implementation manners.

[0022] Referring to Figures 1 to 4 as shown, wherein Figure 2The label 9 therein represents an equivalent transmission line; the label 10 represents a T reference plane; the label 11 represents an equivalent capacitor. The utility model provides a TEM mode capacitive loaded coaxial resonator for a P-band klystron, which includes an outer conductor 1. Both ends of the outer conductor 1 are fixedly connected with a first end plate 3 and a second end plate 4 respectively. A first cavity 8 is arranged inside the outer conductor 1. An inner conductor 2 is arranged inside the first cavity 8. The length of the inner conductor 2 is less than that of the outer conductor 1. One end of the inner conductor 2 is fixedly connected with the side of the first end plate 3 close to the second end plate 4. There is a gap between the other end of the inner conductor 2 and the side of the second end plate 4 close to the first end plate 3, and the gap is L1, and L1 is a constant. There is a gap between the outer side wall of the inner conductor 2 and the inner side wall of the outer conductor 1. A second cavity 7 is arranged inside the inner conductor 2. A first through hole 5 is opened on the first end plate 3. The first through hole 5 is communicated with the first cavity 8 through the second cavity 7. The second end plate 4 is provided with a second through hole 6 along the length direction of the outer conductor 1 and is communicated with the first cavity 8.

[0023] In this embodiment, at a resonant cavity frequency of 324 MHz, a cylindrical outer conductor 1 is constructed. The inner diameter of the outer conductor 1 is 140 mm, the outer diameter of the outer conductor 1 is 170 mm, and the value of L2 in the outer conductor 1 is 250 mm. The value of Φ2 in the inner conductor 2 is 64 mm, the value of Φ1 in the inner conductor 2 is 32 mm, the length of the inner conductor is 205 mm, and the inner conductor 2 is embedded inside the outer conductor 1 to form a concentric circular tube structure. Among them, the second cavity 7 is a cylindrical channel with a diameter of 32 mm. The first through hole 5 and the second through hole 6 are beam channels, and together they form an accelerating gap. The value of L1 is a 45 mm gap, which is designed as an accelerating gap. At one end of the accelerating gap, the outer conductor 1 has a drift pipe with a length of 60 mm, so that the electromagnetic field is cutoff therein.

[0024] Furthermore, the cross-sections of the outer conductor 1, the first cavity 8, the inner conductor 2, the second cavity 7, the first end plate 3, and the second end plate 4 are all circular.

[0025] Furthermore, the first end plate 3, the inner conductor 2, and the second end plate 4 are all coaxially arranged with the outer conductor 1.

[0026] Furthermore, the outer conductor 1, the first cavity 8, the inner conductor 2, the second cavity 7, the first end plate 3, and the second end plate 4 are an integral body.

[0027] Furthermore, the outer diameter of the inner conductor 2 is Φ2, the inner diameter of the inner conductor 2 is Φ1, and the relationship between the outer diameter and the inner diameter of the inner conductor 2 is: Φ2 = 2Φ1; both Φ1 and Φ2 are constants.

[0028] Furthermore, the diameters of the first through hole 5 and the second through hole 6 are both equal to the inner diameter of the inner conductor 2.

[0029] Furthermore, the length of the outer conductor 1 is L2; the relationship between L1, Φ1, and L2 is: Φ1 < L1 < 1 / 5 times L2, and L1 is a constant.

[0030] The TEM-mode capacitively loaded coaxial resonator for P-band klystrons provided by the present utility model has the following working principle: At the accelerating gap, a loading capacitor is formed between the outer conductor 1 and the inner conductor 2. When the sum of the admittances formed by the loading capacitor at the accelerator gap and the inductance formed by the coaxial structure of the outer conductor 1 and the inner conductor 2 is zero, the corresponding working mode oscillation is generated. At this time, a stable resonant electromagnetic field exists in the cavity 1-8. At this time, Figure 1 The capacitively loaded coaxial resonator shown can be equivalent to Figure 3 the equivalent resonant circuit shown. In Figure 3 , with the T reference plane as the dividing line, the left part of the T reference plane is Figure 1 the short-circuited two-wire transmission line equivalent to the coaxial structure formed by the outer conductor 1 and the inner conductor 2 in . According to the transmission line theory, Equation 1-3 can be obtained. Assuming that the capacitively loaded coaxial resonator system is a lossless system, in Equation 1-3, Z in is the input impedance seen from the left of the T reference plane, Z0 is the characteristic impedance per unit length of the coaxial structure, β is the electromagnetic wave phase constant, l is the total length of the coaxial structure, j is the complex number symbol, b is the outer radius of the coaxial outer conductor, a is the outer radius of the coaxial inner conductor, ε and μ are the permittivity and permeability in the free space between the outer conductor and the inner conductor of the coaxial structure respectively, and Y in is the admittance corresponding to Z in ; the right part of the T reference plane is Figure 1 the loading capacitor formed by the outer conductor 1 and the inner conductor 2 at the accelerating gap in . Under the condition that the sum of the admittances of the entire system is zero at resonance, Equation 4-5 can be obtained, where C is the equivalent capacitance of the accelerating gap and ω is the angular frequency of the resonant electromagnetic field. Finally, according to the beam power and the bunching effect, the lengths of the outer conductor 1 and the inner conductor 2, the length of the accelerating gap, and the size of the beam aperture can be calculated, and the specific dimensions in all directions of the three-dimensional structure of the TEM-mode capacitively loaded coaxial resonator operating at the required frequency can be obtained.

[0031] Z in = jZ0tanβl Equation 1

[0032]

[0033]

[0034] At the accelerating gap of the resonant cavity, the electric field is perpendicular to that between the outer conductor 1 and the inner conductor 2. At other positions, the electric and magnetic fields are distributed in the transverse electromagnetic mode. When the linearly moving electron beam passes through the accelerating gap along the axis, the axially distributed electric field at the accelerating gap will accelerate or decelerate the electrons, thus forming the beam-wave interaction. When the resonant cavity is used as the input cavity of a klystron, the small-signal electromagnetic field of the externally input operating frequency establishes an alternating axial electric field at the accelerating gap, and velocity modulates the moving electron beam. The originally linearly moving and uniformly moving electron beam forms velocity modulation after passing through the alternating electric field. The velocity-modulated electron beam forms density modulation after passing through the subsequent drift tube. When the resonant cavity is used as the intermediate cavity of a klystron, when the bunched electron block formed after density modulation passes through the resonant gap of the intermediate cavity, a microwave signal much larger than the small-signal microwave input externally to the input cavity will be excited at the gap. At this time, an alternating electric field is excited at the gap to further velocity-modulate the bunched electron block, thus forming a stronger density modulation. When the resonant cavity is used as the output cavity of a klystron, through design, the highly bunched electron beam passes through the gap of the output cavity at a decelerating phase. At this time, a high-power electromagnetic field signal is excited in the output cavity. Through the decelerating beam-wave interaction, the DC energy of the electron beam is finally converted into high-power microwave electromagnetic field energy. Through output coupling, the microwave energy can be coupled out.

[0035] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0036] The above is only the preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application.

Claims

1. A TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron, characterized in that: The invention comprises an outer conductor (1), wherein two ends of the outer conductor (1) are respectively fixedly connected to a first plugging plate (3) and a second plugging plate (4), a cavity (8) is arranged inside the outer conductor (1), an inner conductor (2) is arranged inside the cavity (8), the length of the inner conductor (2) is shorter than the length of the outer conductor (1), one end of the inner conductor (2) is fixedly connected to a side of the first plugging plate (3) close to the second plugging plate (4), and the other end of the inner conductor (2) is fixedly connected to a side of the second plugging plate (4) close to the first plugging plate (3). ), and the gap is L1, and L1 is a constant; a gap is provided between the outer wall of the inner conductor (2) and the inner wall of the outer conductor (1); a cavity (7) is provided in the inner conductor (2); a through hole (5) is provided on the blocking plate (3); the through hole (5) is connected to the cavity (8) through the cavity (7); and a through hole (6) is provided on the blocking plate (4) along the length direction of the outer conductor (1) and is connected to the cavity (8).

2. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 1, characterized in that: The cross sections of the outer conductor (1), the cavity one (8), the inner conductor (2), the cavity two (7), the blocking plate one (3), and the blocking plate two (4) are all circular.

3. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 1, characterized in that: The blocking plate 1 (3), the inner conductor (2) and the blocking plate 2 (4) are all coaxially arranged with the outer conductor (1).

4. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 1, characterized in that: The outer conductor (1), the cavity one (8), the inner conductor (2), the cavity two (7), the blocking plate one (3) and the blocking plate two (4) are integrated into one.

5. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 1, characterized in that: The outer diameter of the inner conductor (2) is Φ2, the inner diameter of the inner conductor (2) is Φ1, and the relationship between the outer diameter of the inner conductor (2) and the inner diameter of the inner conductor (2) is: Φ2=2Φ1; and both Φ1 and Φ2 are constants.

6. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 1, characterized in that: The diameters of the through hole one (5) and the through hole two (6) are both equal to the inner diameter of the inner conductor (2).

7. The TEM mode capacitor-loaded coaxial resonant cavity for a P-band klystron according to claim 5, characterized in that: The length of the outer conductor (1) is L2; ​​the relationship between L1, Φ1 and L2 is: Φ1<L1<1 / 5 times L2, and L1 is a constant.

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